Communications systems with managed performance on outbound or downlink channels and inbound or uplink channels are becoming more common. This is particularly true for systems that are designed and deployed from the ground up to be interference limited. Being interference limited means that system capacity ultimately depends on the interference at one subscriber or wireless communications unit that results from providing service to other such units. Many systems, such as cellular phone or wireless phone systems that seek to provide satisfactory service to the most units most of the time are interference limited systems.
More recent systems in an effort to maximize system capacity devote significant system overhead to managing downlink signal to interference plus noise ratios (SINR) or link margins such that the power that is used to transmit the downlink signal will be just sufficient to transfer information. A classic example of systems that manage downlink SINR to be just sufficient in order to maximize capacity is IS-95 CDMA (code division multiple access) systems. Determining what is just sufficient is unfortunately a subjective decision that systems designers end up making for the system users. For example a 1% FER (frame error rate) is the target for the downlink performance in IS-95 CDMA systems.
In order to maintain the target SINR the IS-95 air interface standards require that a subscriber unit report performance data corresponding to FER so that the downlink power or SINR can be adjusted to just maintain data transfer at this error rate. If a subscriber device manufacturer discovers a way of improving downlink receiver performance and convinces a user to buy the new receiver, the system automatically takes advantage of the improvement by managing the downlink for this subscriber unit to the 1% FER target and the user does not get any benefit from the improved performance that they may very well have paid for. Thus a situation exists where there is no individual motivation for the collective good and subscriber devices end up evolving to the lowest common denominator in performance. Clearly a need exists for apparatus and methods that can provide a downlink performance benefit in such systems.